Engine Blue Printing - 1275cc A-series - Camshaft #1

DISCUSSION:

• Ok, ready for some heavy weight cam measurements???  Well, I wasn't at first.  I figured it would be simple.  Just figure out the clocking, and you are done...  HA!!!  The cam guys have their own ways to describe these little creatures.  They are almost as complicated as the engine block.
• There are three charts that basically show you three ways to look at the profiling and timing of the cams relative to each other:  linear, normalized and polar.  The data that generates the plots can be seen in the spreadsheet below the graphs.  I apologize for it being a bit small, but if you are really interested, check out the actual Excel spreadsheet that I am using (Engine Blue Printing 1-14-06).
• One interesting thing to look at in the charts below can be seen easily in the second chart, the Lobe Profiles (normalized to 0,0).  The lines should basically be on top of each other for both intake and exhaust.  But, you can see there is some variation in the exhaust profiles.  This difference is probably insignificant, but worth asking a camshaft engineer about.
• Also, a bigger issue... this camshaft as well as the other from engine #2 are mystery cams.  They have no markings on them to indicate what they are.  I was hoping to compare the timing to the cams that I can find in Vizard and on the web, but I have yet to find a match.  I plan to revisit this soon, giving it one more try.  This camshaft has no identification marks that make sense.  The only markings are on the end, "9L73."  Anyone have any ideas?  But, this camshaft is the rare type with the spider drive.
• To generate some of the data and graphs, I had to find some "Add-In" components for Microsoft Excel.  You will need to add them to tweak certain parts of my spreadsheet.  I use two tools: Polar Plot (from Andy Pope) and XlXtrFun (from Advanced Systems Design and Development).  All you have to do is follow their directions and then activate both.  Add-Ins activation can be found under the Tools menu in Excel.  Thanks guys for some great tools and making it possible for me to display my data.

SUMMARY:

• Cam #1 is a really good cam with no visible issues.  All lobes are shaped the same relative to intake and exhaust profiles.  And, there are no visible cracks, chips or other questionable operating history.  Thus, hopefully it's perfect for a regrind, but there's always that crack issue that has to be inspected.

• This setup is the core of the cam measurements.  It allowed me to take cam lobe lift measurements every 6 degrees.  The 360 degree protractor was purchased at Office Depot and the PVC adapter was machined on my lathe to lightly press onto the camshaft using your hand.  The protractor and PVC adapter are double stick taped together.  While I am thinking about it, all of this measurement equipment can be purchased at any machine shop supply company.  One of the best for mail order is MSC Industrial Supply.  But, there are other companies that you might find locally, like Rutland Tool & Supply.  I think even Harbor Freight has some of the routine measurement equipment.  The dial bore gauge will need to be purchased from a real machine shop supply company.  And, for engine blueprinting at our level (non-professional racing), you don't need things like CMMs and air gauges.

• This setup shown in the next four photos utilized gauge blocks and a feeler gauge to determine if the cam was straight.  First, the cam was level on each end.  Then, gauge blocks were stacked in the center until a feeler gauge could be used to measure the remaining gap.  The maximum gap was easy to find using the feeler gauge and rotating the cam through 360 degrees.  It turns out, just like the rest of the engine #1.  The cam is only out of straightness by 0.0001".  Thus it's on the very limit of my measurement capability.

• As a reference, I have included Comp Cam's chart that explains everything you need to know about measuring a camshaft.
  
  

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